Question

I am facing a situation where I need to add the same blocks of code to the start and the end of multiple functions in JavaScript. e.g.

function funcA () {
    // code block 1
    ...

    // code unique to funcA
    ...

    // code block 2
    ...
}

function funcB () {
    // code block 1
    ...

    // code unique to funcB
    ...

    // code block 2
    ...
}

function funcC () {
    // code block 1
    ...

    // code unique to funcC
    ...

    // code block 2
    ...
}

I wonder what is the right pattern to use here to minimize the duplications.

Answer 1

You could use another function to build your functions for you:

function makeFunc( specialProcessing ) {
  return function() {
    // block 1
    specialProcessing( x, y, z );
    // block 2
  };
}

var func1 = makeFunc( function( x, y, z ) {
  // stuff for func1
});

var func2 = makeFunc( function( x, y, z ) {
  // stuff for func2
});